What is DNS/DDNS?
The Domain Name System (DNS) is a hierarchical decentralized naming system for computers, services, or other resources connected to the Internet or a private network. It translates more readily memorized domain names to the numerical IP addresses needed for locating and identifying computer services and devices with the underlying network protocols. DNS delegates the responsibility of assigning domain names and mapping those names to Internet resources by designating authoritative name servers for each domain.
Dynamic DNS (DDNS or DynDNS) is a method of automatically updating a name server in the DNS, often in real time, with the active DDNS configuration of its configured hostnames, addresses or other information.DDNS captures the change of the IP address and corresponding domain names can be quickly re-mapped to new IP address in order to maintain accessibility using a previous URL.
DNS: If you enter some website domains name like www.google.com, DNS will translate the name into a numerical IP address.
DDNS: You can bind a fixed domain name to the router, you can access the router through the domain name in spite of the change of IP address.